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TOPIC 9 : WASTE MANAGEMENT
Waste refers to unwanted materials produced by human activities.
CLASSIFICATION OF WASTES
Wastes can be classified based on different criteria; physical state and degradability.
CLASSIFICATION BASED ON PHYSICAL STATE
Based on physical state, wastes can be classified as solid wastes, liquids wastes, gaseous
wastes and sludge wastes
CLASSIFICATION BASED ON DEGRADABILITY
Based on degradability, wastes can be classified as:
Biodegradable wastes. These are wastes that can decay relatively quickly as a result of
the action of bacteria. They include animal and plant waste.
Non–biodegradable wastes. These are wastes that do not decompose naturally.
Examples include plastics and glass.
SOURCES OF WASTES
a. Domestic sources: These wastes include food leftovers, plastics, metals, untreated
sewage, expired or unused medicines and their containers.
b. Industrial sources: These include used oil, toxic gases, metals and plastics etc.
c. Agricultural sources: These include plant remains excess agricultural chemicals such as
pesticides, herbicides, and weedicides.
d. Medical sources: These are wastes from medical centres and hospitals. Examples are
plastics, glassware, expired drugs, used syringes, needles, cotton and detergents.
e. Laboratory sources: These include expired chemicals, contaminated chemicals, broken
glassware and detergents.
WAYS OF TREATING AND DISPOSING WASTE
a. Open burning
Wastes such as papers, plastics are usually burnt to ashes in open land. This method is
discouraged because it causes air pollution due to emission of harmful greenhouse gases.